1. Field of the Invention
The present invention relates to a packet routing method for the mobile node in the wireless sensor network, more particularly to a routing method and routing path recovery mechanism applied in the wireless sensor network environment.
2. Description of the Related Art
In general, the Internet Protocol Address (IP address) is used to identify the nodes in the internet. On the other hand, regarding the local area network (LAN), the Media Access Control Address (MAC Address), which represents the physical address of the Ethernet card, is a common means to determine the nodes in the local area network. Similarly, in the wireless sensor network, each mobile node requires an identification code, so as to recognize each other and carry the network packets to the correct destination.
In the wireless sensor network environment, a physical network includes three major parts: the mobile node, the gateway, and the management unit. The mobile node can be any physical network device in the wireless sensor network, and connects each other, to form a tree structure network topology. The gateway is the root node in the tree structure network topology for connecting the mobile nodes in the wireless sensor network to the management unit, or connecting multiple wireless sensor networks to a common management unit. By wireless or wired connection, at least a gateway is utilized for connecting the management unit. Last, the management unit is composed of one or multiple physical network devices, which are connected to the gateway by wire or wireless, for managing the operation of one or multiple wireless sensor networks.
However, the topology of wireless sensor network will be changed constantly due to the damage to the mobile node, or due to the movement of the mobile node. In such circumstance, the routing path should be recovered, and methods for recovery will differ from different types of ID codes.
There are two types of ID codes: routable ID code and non-routable ID code and accordingly two common implements for ID code distribution: Routable ID Distribution Mechanism, and Non-routable ID Distribution Mechanism. The routable ID distribution mechanism (e.g. Zigbee) denotes that the ID code itself carries the routing information. It can perform packet routing solely based on the ID code without any additional route table. Thus, when the network topology changes, the routable ID distribution mechanism has to redistribute the ID codes to mobile nodes and any node in their each sub-trees; otherwise, the routable ID distribution mechanism would not work. However, the redistribution of ID codes not only requires a huge amount of information exchange, but also a long redistribution time so that it would cause disconnection between nodes. That is, the routable ID distribution mechanism is not capable of supporting mobility and fault tolerance. Hence, the mechanism does not work well when a node is damaged or changes its position in the tree topology. Additionally, the non-routable ID distribution mechanism utilizes a routing table to perform packet routing. That is, by using this mechanism the system does not have to redistribute the ID codes, but need to refresh the routing table constantly on any relevant nodes. Same, the refresh method in the non-routable ID distribution mechanism would generate huge amount control messages, and require transporting this information to all nodes. The significant work loading would increase the system burden, and the transporting process would expend more refreshing time. In sum, the non-routable ID distribution mechanism cannot rapidly recover the routing path in real-time manner.
Therefore, to solve the above-mentioned problems, the present invention proposes a novel path routing method and a routing recovery mechanism. The operation of the routing method and the relevant implements are detailed as follows.